Temperature problem
Temperature problem
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Discussion

Mr.Snood

Original Poster:

70 posts

205 months

Sunday 18th September 2011
quotequote all
I have a weird temperature problem.

Situation:
30 miles highway
5th gear
~3200 rpm
120 KPH (75 MPH)
Temperature is stuck at ~93°C (~200°F)
Everything is fine...


Putting the car in 6th gear
~3200 rpm
160 KPH (100 MPH)
After a few seconds temperature is stuck at ~98°C (~209°F)

Pushing the car brings the temperature pretty fast around 100° (or higher).


The Fan kicks in (not sure at which temperature), but it does.
The water circuit doesn't have any leaks, at least I can't find some.

I assume that around 98°C it starts to loose water through the overflow spring (while driving).
Because the water from the overflow tank is gone at some point.
But again: I can't find any leaks when the car is standing apart a couple of water drops behind the car on the road.

Probably a broken thermostat?
Would that make any sense?



MarkWebb

983 posts

241 months

Sunday 18th September 2011
quotequote all
Over flow tank is empty on mine as well with no water leaks. However swirl pot is completely full. Water from overflow tank will get sucked back into swirl pot if there is air in system until such a time as the swirl pot is completely full after a drive and the engine has cooled. If you put water into overflow tank then it will get blown out. I think that a volume of air equivalent to the overflow tank is needed to absorb the increase in pressure as the engine warms up.
As long as the swirl pot is full then you have no problem with water leaks or air. The temp sensor is on the engine but the fan sensor is in the radiator. Some people have bought fan stats that cut in at a lower temp. Water does not boil until 120 deg + when at the pressure that the cooling system allows. However engine should not get that hot when driving at speed so prob air in system or faulty stat.

Edited by MarkWebb on Sunday 18th September 17:50

Mr.Snood

Original Poster:

70 posts

205 months

Sunday 18th September 2011
quotequote all
Thanks.
Swirl pot is/was always full.

I suppose the stat doesn't open the cooling circuit.
I'll do another test drive tomorrow:
Bring the car to heat, and check the radiator / hose temperature...

Steve_D

13,801 posts

282 months

Sunday 18th September 2011
quotequote all
My car runs with about an inch of coolant in the expansion tank when cold. If I put any more in it just spits it out. GTRmikie has mentioned before that his has none visible when cold.

Steve

srreck

529 posts

285 months

Monday 19th September 2011
quotequote all
I would check the thermostat (open the swirl pot, start the engine and wait for working temp) and the water pump flow.

V8 Vum

3,206 posts

245 months

Monday 19th September 2011
quotequote all
LS7 right?

I have SPA dials and dash, so I have used the External Alarm circuit in the Water temp gauge (sensor off the head - there is one for the ECU and I used the other head for the dash sensor) - There are 2 alarms on ths SPA unit, one internal (turns on red light) which I have set for 110 degrees, and the external one to 98 degrees. The external alarm wire goes to a amall relay that switches the larger fan relay... So now I can adjust the switch on temp to whatever I like! ..and it is read from the Engine head, not the front Rad. I have left the rad sensor in the circuit anyway as a backup! Works well it seems.

Mr.Snood

Original Poster:

70 posts

205 months

Sunday 25th September 2011
quotequote all
LS7, yes.

Did some more testruns, and it's definitely not losing any water,
but still getting to hot under load or above 100 MPH.

The original water pump leaked and I had to replace that a couple of months ago.
This is when the problem started to arise.
Is the replacement pump probably not powerful enough?

What water pump are you using?
Is there any part number I can check?
Or minimum water flow I need?

Gulf LS3

1,922 posts

228 months

Sunday 25th September 2011
quotequote all
how hot has she got?

Mr.Snood

Original Poster:

70 posts

205 months

Sunday 25th September 2011
quotequote all
Hit 110°C for a couple of seconds yesterday on Track,
then I had to stop the session and give it a break.
Most of the time it was between 98°C and 101°C


Steve_D

13,801 posts

282 months

Sunday 25th September 2011
quotequote all
Where are these temperatures being measured?

Steve

Mr.Snood

Original Poster:

70 posts

205 months

Sunday 25th September 2011
quotequote all
No idea.

Where shall I look for the sensor, and how does it look like? :/

SchimmS

258 posts

282 months

Monday 26th September 2011
quotequote all
Mr.Snood said:
No idea.

Where shall I look for the sensor, and how does it look like? :/
Hi Sven,
I talked to the engine builder yesterday and he said the reason for the temp change can`t be the result of the waterpump change as there`s only 1 OEM model for LS3, LS7, etc engines. The only thing he could think of was that the system wasn`t bled properly - call me today, I`ll give you some more info.